Mechanical shovel for scotch hearths



Dec. l0, 1935. H. R. MaCMlcl-IAEL 2,023,483

MECHANICAL SHOVEL FOR SCOTCH HEARTHS Original Filed June Z5, 192'? 3 Sheets-Sheet 1 Dec. l0,l 1935. H. R. MacMlcHAl-:L 2,023,483

MECHANICAL SHOVEL FOR SCOTCH HEARTHS originar Filedu June '5, 1927 s sheets-sheet 2 Dec. l0, 1935.

H. R. MaoMlcHAl-:L 2,023,483

MECHANICAL SHOVEL FOR SCOTCH HEARTHS Original Filed June 3, 1927 3 Sheets-Sheet 3 Patented ec. ii), i935' UNITED. STATI-:s

PATENT OFFICE MECHANICAL sHovEL Fon a scoren HEAa'rns 1 Application June 3, 1927, Serial No. 196,304

Renewed April 9, 1929 38 Claims. (Cl. 26S-24) u The invention relates to a process of and apparatus for metal smelting, and, more particularly, to a mechanical shovel for-shoveling and spreading the charge of a vScotch hearth type furnace.

According to the invention, a-Scotch hearth is provided with a mechanical shovel or spreader, which may be positioned on a suitable carriage running along in front of the hearth. I'he carriage may have also mounted thereon, a suitable mechanical rabbler. The mechanical rabbler may poke the charge and lower it throwing part of it on the apron, while the mechanical shovel may follow and push the charge baci: up against the water back of the hearth, so that the charge is distributed to form a bank having desirable characteristics. The mechanical shovel may take the place of a workman for this purpose. The charge of ore and fuel may be fed onto the hearth either manually or by special mechanical feeding devices.

A further feature of the invention is to provide a mechanical shovel or spreader which will pile the charge up against the water back of the hearth into a bank having such an angle ofrepose that the different particles will roll forward different amounts' depending on the size, giving a select-ive action. According to the selective action the larger particles roll forwards the farthest while the nest particles do not roll forward any The intermediate particles' or impairing the condition of the charge for' proper sinelting, in any way.

Various other features and advantages of the invention will be apparent from the following particular ydescription and from an inspection of the 'accompanying drawings.

rlhe invention also consists in certain new and original features of construction and combinationsdof parts hereinafter set forth and claimed. Although the novel features which are believed to loe characteristic or this .invention will be pointed out with particularity in the claims.ap pended hereto, the invention itself, as to its objects and advantages, the mode'of its operation and the manner of its organization may be better understood by referring to the following description taken in connection with the accompanying drawings forming a part thereof, in which Fig. 1 isl a front elevation showing a typical Scotch hearth witha conventional track and car-f4 riage running in front, the carriage being provided with the improvedmechanical shovel;

'Fig 2 is adetail showing a section through the Scotch hearth, and a side elevation of the mechanical shovel;

Fig. 3 is a top plan view of a detail of the 15 shovel taken on the line 3--3 of Fig. 2;

Fig. 4 is a front elevation similar to Fig. 1

but showing the device enlarged;

Fig. 5 is a sectionon the line 5--5 of Figs. 4 and 6, showing details of adjusting mechanism for adjusting the movement of the shovel;

Fig. 6 -is a top plan view, partly in section on the line E-5 of Fig. 5, showing a further detail oi the adjustingmechanism; and

Fig. 7 is a section on the line Tl-i of Fig. 2; 25

Fig. 8 is an enlarged detail of the shovel blade and handle;

Fig. 9 is a section on the line 9 9 of Fig. 5, showing a detail of the composite lever and adjusting mechanism.

In the following description and in the claims parts will be identified by specific names for convenience, but they are intended to be as generic inr their application to similar parts as the art will permit. 35

ILike reference characters denote like parts in the several gures of the drawings.

Referring now to the drawings, and, more particularly to Figs. l and 2, a'well known type of 40 Scotch hearth smelting furnace is shown, comprising a trough or basin i having an a'pron 2 at its front end suitably secured thereto. The back of the furnace comprises a water block 3 having a hollow chamber #l through which water may be circulated, the lower portion of the block having spaced intake openings of tuyres 5 extending along the length of the furnace for supplying the fire with a draft. The upper portion of the furnace may have suitable hoods or canopies B to catch the gases and fume which are given off by the ore, as is well understood in the art.

Extending along the front of the furnace and supported by suitable columns 1, is a track 8 on which is mounted a carriage 9 having supporting wheels I0 and a framework II depending to a suitable position for supporting the operating tools so they may extend from the carriage under the hoods. Mounted on this framework may be suitable mechanism for imparting motion to the carriage along the furnace, so that the apparatus carried thereby may be used to operate upon the entire length of the furnace.

Any suitable mechanism may be provided for imparting either a step by step motion to the carriage, or a. continuous motion to the carriage, this mechanism also imparting to the crank shaft I2 a continuous rotary motion. t

A wheel I5 may be secured to the crank shaft having a suitable cam surface I6 and a crank pin I1 near its outer edge, this crank pin being suitably secured to the wheel and having a clamp I8 inpwhich may be disposed a poker or rabbler (not shown), for rabbling the furnace charge.

The clamp I8 may be of any suitable construction, and in the embodiment shown is composed of a lower U-shaped member I9 to which is pivotally connected a link 20 which may be locked in closed position by a pin or similar device 2|, to hold the handle of the rabbler. To the outer end of the clamp I8 a grooved roller 22 may be mounted to engage guides or ways 23 on the impeller arm 24, to be described hereinafter more in detail.

Projecting sidewardly from the carriage is a pair of angle irons, 25, on the topy of which is secured a top plate 28. 'I'his top plate, which is generally flat, has depending therefrom a pair of spaced ears 29 (Figs. 2 `and 4) to which the impeller arm 24 is pivotally connected, and a second pair of spaced ears 30 to which a composite lever 3i may be connected. At one side of the plate 28 an upstanding lug 32 is provided to which may be suitably bolted an upstanding bracket 33 having a collar 34 at its upper end, in which an opening is disposed. The top plate is provided with an opening aligned with the opening in the collar, and screw threaded holes 35 are provided on either side of the second opening in which may be threaded rods 36, the rods being connected at their upper ends by means of a plate 31, the lplate being positioned between suitable nuts. l 1

Disposed in the aligned openings is a follower rod 88 having at its lower end a tapped hole in which.may be disposed a forked follower member 38 the stem of this member being threaded into the opening and locked therein by means of a large locknut 40. The prongs of the fork have positioned therebetween a roller 4I which is suitably ;lournalled in the prongs,this roller engaging the-cam surface on the cam wheel I5.

The follower rod 438 is provided with a suitable abutment 44 between whicl and the plate 31 is disposed a coil spring 45, this coil spring acting to continuously urgevthe follower rodagainst the cam surface. I

Pivotedpbetween the ears 28 by means of a.

suitable pivot bolt is an impeller arm 24 being curved at its upper end and generally'straight for the rest of its lengthj this impeller arm having secured to one side thereof a pair of spaced lugs 48. A` pair of spaced Ways or guides 23 is secured to lthe lugs these ways or guides being c'urved, as shown in Fig. 2, to aid in giving the desired peculiar motion to the shovel blade 41. The grooved roller 22 on the end of the crank pin is disposed between these ways.

Pivoted at the lower end of the impeller arm 5 24 is a shovel arm 48, this arm comprising a body member 48 having an opening in its middle portion, forming branches 50 (Fig. 3) between which the lower end of the impeller arm is disposed. A

suitable pivot bolt threads the branches and the 10 impeller arm. The front end of the body is suitably forked, and between the prongs of the fork 5I the lower end of the elevating link 52 is suitably pivoted by means of a pivot bolt. The rear end of the shovel arm body 49 is provided with 15 an opening in which the end of the shovel rod 53 is disposed, the shovel rod being clamped therein by means of a suitable set screw 54. The rear end of the shovel rod has a depending flange, to which is secured the blade 41 of the shovel which 20 extends longitudinally of the furnace a substantial amount and has a slightly back curved lower end, 51, as' shown clearly in Fig. 8.

Pivoted between the spaced ears 30 is a composite lever 3| made up of two parts, one part 25 being adjustable axially with respect to the other. These two parts always maintain a definite angular relation. One part 58 is maintained axially fixed and will be called for convenience, the fixed part, whereas the other part 59 may be 3u moved axially, and will be termed for convenience, the movable part. The xed part is fixedly securedto the shaft 60 by means of a key 6I and set screw 62, the shaft being mounted in suitable bearings in depending ears 30. Pro- 35 jecting laterally from the collar 63 of the fixed member is a fork 84 having elongated openings 65 disposed therein. Disposed within these elongated openings is a pivot rod 66 which pierces the lower end of the follower rod 38, this pivot rod be- 40 ing fixed in the follower rod, but is allowed a small movement in the elongated slots, this construction being clearly shown in Figs. 4, 6, and 9.

The movable member 59 comprises a collar 81 which is loosely mounted on the shaft and has (5 a pair of axial projections 88 which engage the fiat portions or ways 88 on the collar of the xed member, this being shown clearly in Figs. 6 and 9. Secured to the collar 61 of the movable member is a fork 1D in which is pivoted by means of a pivot 50 bolt, a cross member 1I pivotally connected with the elevating link 52 so that there is a universal motion between the composite lever 3l and the elevating link 52.

The upper end of the elevating link is forked 55 to embrace the cross member, a suitable pivot bolt threading the /prongsM of the fork and the cross member. IThe 4elevating link comprises generally three sections (Fig. 2), the lower end of the upper section 15 being threaded. The upper end of the 60 intermediate section 16 is also threaded, these ends being held together by means of a suitable turnbuckle 11 having lock nuts for locking the turn buckle in adjusted position.

I'he lower end of the intermediate section 18 65 is provided with a stepped bore. in which is disposed the upper end of the lower section 18. The upper end of the lower section has a smaller piston 18 which fits into the smaller bore, and a larger piston 80 which fits into the larger bore. A 70 threaded collar 8|` is threaded into the lower end of the larger bore. Between the larger piston and the shoulder 82 connecting the larger and smaller bores, a coil spring 83 is disposed, and a coil spring 84 is also disposed between the larger 75 piston 80 and thethreaded collar. 'I'he construction including the coil springs allows a relative, reciprocating, elastic movement' between the lower and intermediate sections of the elevating link, this action and its contributing effect being described hereinafter.

in the forked member 81, a suitable collar 90 being pinned to the spindle 89 and disposed between the prongs of the fork 81 to x the axial position of the spindle. The spindle has a hand wheel 9| at its outer end, by means of which it can be moved to change the relative position of the movlable and fixed members.

It will be seen that this mechanism is provided with the following adjustments, the rstbeing the hand wheel 9i which is turned to change the distance between the pivot points on the depending ears 29 and 30. This is used for adjusting the elevation of the shovel blade 41 at its back position or at the end ofits stroke. Another adjustment is that of the turn buckle 11 which changes the effective length of the elevating link 52, this being used to x the elevation of the shovel blade at the beginning of its stroke, or at the front of the furnace on the apron 2.

Furthermore, the guides 23 are easily detachable from the impeller arm-24 so that different shapes of guides may be used to obtain different operating actions. For the same reason the cam wheel I may be replaced by cam wheels having different cam surfaces. The shape and angle of the shovel blade 41 and the tip 51 may also be adjusted or changed to give different operating characteristics. It will be understood that these changes or adjustments are desirable to take care of different operating conditions imposed by various causes such as ,changes in the ore.

In operation, after the rabble has operated upon the charge, it lowers the charge down to a line somewhat as indicated by the dotted line S4, part being thrown on the apron 2. The shovel follows and the lower back-turned edge 51 of the blade 41 describes a closed path indicated by the dotted line 95. The mechanism has been designed to give this shovel a peculiar andeiiicient motion. The detail movement of the shovel blade is quite involved, depending upon the relative size of thel several levers, the adjustments, the shape of the ways 23 and cam wheel I5, and on the action of the springs 83 and y84. The shovel blade is caused to operate relatively slowly while it is scraping the apron, and while it is moving over the front and the middle of the trough. At substantially the back of the stroke the blade is caused to travel abruptly upwardly, at the same time its speed is suddenly increased to cause it to flip part of the charge up against the water back, whence it settles down on a line which is determined by the angle of repose of the different particles. This line under some ,conditions may be as indicated by 96.

A selective action is obtained. The coarser" particles roll further down the bank, while the finer particles remain up near the top, the particles being Yselectively disposed, ranging from the nest material near the tcp to the coarser material and large slag lumps near the bottom. The larger particles, the majority of which are slag,

roll all the way down upon the apron where they may be easily removed and taken lto a proper place.

It is very important that this'spreading and shoveling action be obtained without packing the 5 l material. Prior to the invention it was very difiicult to keep the fire going, and it was especially diflcult to keep the fire burning evenly and to prevent craters from forming. The re was liable to break through and burn brightly in spots while other spots are comparatively cold, if preventa tive means were not taken. vBy the action given by the mechanical' shovel of the invention the fire is maintained uniform throughout the extent of the hearth.

lThe finer materials near the top and back prevent the fire from breaking through and forming craters, in which position this is generally most likely to happen, while the coarser materials near the front and bottom allow the 2o air to pass through at this region, causing the fire to burn substantially uniformly throughout the extent of the entire furnace. The mechanical shovel not only saves the exhausting'manual labor formerly required to do this work, but does l25 it much better and more uniformly than it could be done manually.

While certain novel features of the invention have been shown and described and are pointed out in the annexed claims, it will be understood that various omissions, substitutions and changes in the forms and details of the device illustrated and in its operation may be made by those skilled in the art without departing from the spiritof the invention.

What is claimed is:

l. In combination with a Scotch hearth having a longitudinally vextending trough and apron, mechanical shovel mechanism comprising a carriage adapted to move along in /front of said hearth, said carriage having a support, an impeller arm pivotally connected to said support, a shovel arm pivotally connected to said impeller arm, a shaft having a cam, a follower mount- -end of said lever and pivotally connected e for adjusting the length of said elevating link,

ed in said support, a spring device urging said follower against said cam, a lever pivotally connected to said support and having one end pivotally connected to said follower rod, an elevating link pivotally connected with the other to said shovel arm, said impeller arm having a guide, said shaft having a cross head in operative relation torsaid guide, said shovel arm having a nblade at its backend.

2. In combination with a Scotch hearth having a longitudinally extending trough and apron, mechanical shovel mechanism comprising a car- -riage adapted to move along in front of said hearth, said carriage having a support, an irn-` peller arm pivotally connected to said support, a.

said link having upper and lower sections with spring means therebetween to allow relative, longitudinal, elastic, movement between said sections, said impeller arm having a guide, said crank shaft having a cross head in operative refrom said support, a shovel arm pivotally con-` nected to the lower end of said impeller arm, a crank shaft having a cam, a follower rod vertically mounted in said support, a spring device urging said follower rod against, said cam, a lever lpivotally connected to said support and having one end pivotally connected to said follower rod, an elevating link in front of said impeller arm, said link being pivotally connected with the other end of said lever and pivotally connected to said shovel arm, said link having upper and lower sections with spring means therebetween to allow relative, longitudinal, elastic, movement between said sections, said impeller arm having a longitudinal guide, said crank shaft having a cross head in said guide, said shovel arm having a blade at its back end, said blade having a backturned lower edge.

4. In combination with a Scotch hearth havin a longitudinally extending trough and apron, mtg chanical shovel mechanism comprising a carriage adapted to move along in front of said hearth, said carriage having a support well above said trough, an impeller arm pivotally depending from said support, a shovel arm pivotally connected to the lower end of said impeller arm, a rabbler crank shaft having a cam, a follower rod` vertically mounted in said support, a spring device urging said follower rod against said cam, a composite lever pivotally connected to said support, said composite lever comprising an axially fixed part pivotally connected to said follower rod and an axially movable part, means for adjusting said movable part relatively longitudinally to said xed part, an elevating link in front of said impellerA arm and having universal connection with said movable part and pivotal connection to said shovel arm, means for adjusting the length of said elevating link, said link having upper and lower sections with spring means therebetween to allow relative, longitudinal, elastic, movement between said sections, said impeller arm having a curved longitudinal guide, said camhaving a socket for a rabble arm and a cross head in said guide, said shovelarm having a blade at its back end, said blade having a backturned lower edge. f

5. In combination with a hearth, mechanical l shovel operating mechanism comprising a support, an impeller arm pivotally connected to said support, means for imparting an oscillating motion to said impeller arm, anoperating .arm pivotally connected to said impeller arm, a shovel blade on said operating arm, a guide .mounted on said support, a slide member mounted on said guide to move generally transverse to the length of said operating arm,'a link piv-- 6. In combination with a hearth, mechanical operating mechanism comprising a support, an impeller arm pivotally connected to said support, means for imparting an oscillating motion to said impeller arm, an operating arm pivotally ,l connected to said impeller arm, a link pivotally 5 connected to said operating arm and support, and means for imparting a longitudinal motion to said link and meansfor adjusting the distance between the points where said impeller arm and elevating link are pivotally connected to said support.

7. In combination with a Scotch hearth having a longitudinally extending trough, mechanical shovel mechanism comprising a carriage adapted to move along in front of said hearth, said can'iage having a support, an impeller arm pivotally connected to said support, a shovel arm having a shovel blade at its back end and pivotally connected to said impeller arm, a link pivotally connected to said shovel arm and support, and means for imparting an oscillating rotary motion to said impeller arm and a longitudinal motion to said link, whereby said shovel blade has imparted thereto a sudden ip.

8. In combination with a Scotch hearth having a longitudinally extending trough, mechaniical shovel mechanism comprising a carriage adapted to move along in front of said hearth, said carriage having a support, an impeller arm pivotally connected to said support, a shovel arm having a shovel blade at its back end and pivotally connected to said impeller arm, a link pivotally connected to said shovel arm and support, and means for imparting an oscillatingv rotary motion to said impeller arm and a longitudinal motion to said link, whereby said shovel blade has imparted thereto a sudden flip and means for adjusting the distance between the points where said impeller arm and elevating link are "pivotally connected to said support.

9. In combination with a hearth, mechanical operating mechanism comprising support, an impeller arm pivotally connected to said support, means for imparting an oscillating motion to said impeller arm, an operating arm pivotally 4.5 connected to said impeller arm, a linkpivotally connected to said operating arm and support, and means for imparting a longitudinal motion to said link, said link being made up of two sections with an elastic device therebetweenl 10. In combination with a Scotch hearth having a longitudinally extending trough and apron, mechanical shovel mechanism comprising a carriage adaptedto move along 'in front of said hearth, said carriage having a support, an impeller arm pivotally connected to said support, means for imparting an oscillating motion to said impeller arm, a shovel arm having a shovel mechanical shovel mechanism comprising a carriage adaptedy to move along in front of said hearth, a shovel arm having a generally vertical shovel blade4 at its back end, said blade having a backwardly/.extending flange at its lower edge, said arm extending forward generally horizontally so, thatsaid blade `may substantially scrape said apron, means for imparting a generally reciprocating motion to said arm in the general direction of the length thereof, and means for imparting a motion to said blade in a direction transverse to the rst motion whereby to cause said blade to give part of the charge an upward flip towards the back of said hearth at the region near the back of said trough.

12. In combination with a hearth having a longitudinally extending trough, mechanical shovel mechanism comprising a carriage adapted to move along in front of said hearth, a shovel arm having a shovel blade at its back end, said arm extending forward generally horizontally,

means for imparting a generally reciprocatingl motion to said arm in the general direction of the length thereof, and means for imparting a motion to said blade in a direction transverse to the first motion.

13.. In combination with a hearth, mechanica shovel mechanism comprising a shovel blade adapted to move over said hearth, and means for giving said shovel blade a sudden flip in its motion over said hearth. p

14. In combination with a hearth having a back, trough and apron, mechanical shovel mechanism comprising a shovel blade, and means for causing said blade to move backwards across said apron and trough, said blade substantially scraping said apron and means f or causing said blade to then give part of the charge a sudden ip against the back.

.1'5Trn combination-with a hearth having a back and trough, mechanical shovel mechanis comprising a shovel blade, means for caus' g said blade to move back across said trough and means for causing said blade to give part of the charge a sudden iiip up against said back.

16. In combination with an ore hearth having a longitudinally extending trough and a longitudinally extending apron sloping forwards and slightly downwardly from the front edge of said trough, a back extending up from the back of said trough, a shovel blade comprising a iiat body having a backturned lower edge, means for imparting the following motion to said shovel bladez-the path beginning with a slope backward and slightly upward over the surface of the said apron and over the front part of said trough, thepath thus far being disposed at approximately right angles to said body, the slope 4of said path then becoming steeper, the path extending abruptly upwardly and the speed of the blade being suddenly increased as the blade reaches its backmost position, to give part of the charge being pushed an upward flip against said back, the path then extending forwardly above the charge to the starting point.

17. In combination with an ore hearth having" a longitudinally extending trough and a longitudinally extending apron sloping forwards and slightly downwardly from the front edge of s'aid trough, and a back extending up from the back of said trough, a shovel blade comprising a flat` body having a back-turned lower edge,A anarm connecting said shovel blade and extending forwards over said apron, means for imparting the following motion to said shovel bladez-the path beginning with a slope backward and slight-ly.

creased as the blade reaches its backmost position to give part of the charge being pushed an upward flip against said back, the path then extending forwardly above the charge to the starting point. 5

18. In combination with a hearth mechanical operating mechanism comprising a. support, an impeller arm pivotally connected to said support, an operating arm pivotally connected to said impeller arm and extending back over said hearth, 10 said impeller arm having a longitudinal, curved guide, and aA shaft having a crank with an element co-operating with said guide.

19. In combination with a Scotch hearth having a longitudinally extending trough, mechani- 15 cal shovel mechanism comprising a carriage adapted to move along in front of said hearth, said carriage having a support well above said trough, an impeller arm pivotally depending from said support, a shovel arm pivotally connected 20 said trough, an'impeller arm pivotally depend- 'ing from said support, a shovel arm pivotally connected to the lower end of said impeller arm and extending back over said hearth, said impeller 35 arm having longitudinal, spaced, curved guides concave towards said hearth, a shaft having a crank with Aa roller between said guides, and means for imparting a vertical motion to the back end of said shovel arm at proper times. 40 21. In combination with a hearth, mechanical operating mechanism comprising asupport, an impeller arm pivotally connected to said support, said impeller arm having a longitudinal, curved guide, a shaft having a crank' with an element 45 co-operating with said guide, a link pivotally connected to said support, said linkbeing made up of two sections with an elastic device therebetween, means for impartinga longitudinal motion to said link, and an operating arm pivotally 50 connected to said impeller arm and link.

22. In combination with a Scotch hearth having a longitudinally extending trough and apron, mechanical operating mechanism comprising a support, an impeller arm pivotally depending 55 from said support, said impeller arm having a longitudinal, curved guide concave towards said hearth, -a shaft having a crank with an element cooperating with said guide, a link pivotally depending from said support, said link being made 60 up of two sections withan elasticdevice therebetween, means for imparting a longitudinal motion to said link, an operating arm pivotally connected to said impeller arm and link, and a shovel blade at the back end of said operating arm and 65 disposed over said hearth.

23. In combination with a hearth, mechanical operating mechanism comprising a support,an impeller arml pivotally connected to said support, said impeller `arm having a longitudinal, curved guide, a shaft having a crank with an element cooperating with said guide, a link pivotally connected to said support, elastic devices, an operating arm pivotally connected to said impeller arm land link, means for imparting a transverse mo- 75 tion to said operating arm including said link and elastic devices.

24. In combination with a hearth, mechanical operating mechanism comprising a support above said hearth, a composite lever pivotally mounted on said support and comprising an axially xed part and an axially movable part, means for connecting said parts so as to allow relative axial motion but no relative angular motion, an elevating link pivotally connected to said movable part, a motion imparting element pivotally connected to said fixed part, an impeller arm pivotally depending from said support in back of said link, an operating device pivotally connected to said impeller arm and link, and means for oscillating said impeller arm.

25. In combination with a hearth, mechanical operating mechanism comprising a support, a composite lever pivotally mounted on said support and comprising an axially fixed part and an axially movable part, said parts having angularly fixed relation, a link pivotally connected to said movable part at a pivot point, a motion imparting element driving said fixed part, an impeller arm pivotally mounted on said support at a second pivot point and means for adjusting the distance between said pivot points by moving said movable part, an operating device pivotally connected to said impeller arm and link, and means for oscillating said impeller arm.

2'6.^'`In combination with a Scotch hearth having a longitudinally extending trough and apron, mechanical shovel mechanism comprising a carriage adapted to move along in front of said hearth. said carriage having a support well above saidtrough, a shaft journaled in said support, a composite lever comprising an axially fixed part secured to said shaft and having a keyway, an axially movable part on said shaft having a key fitting said'keyway, depending ears on said parts, a spindle disposed in said ears, an elevating link pivoted to said movable part at a pivot point, a motion imparting element pivoted to said fixed part, an impeller ann pivotally depending from said support at a pivot point in back oi.' said link, and means for adjusting the distance between said pivot points by moving said spindle, a shovel device pivoted to said impeller arm and link, and means for oscillating said impeller arm.

27. In metallurgical apparatus, a hearth com-` prising a trough and a hood fitting closely thereover, a shovel comprising an-arm and blade, said arm disposed at substantially the same level as said trough, and means for operating said shovel.

28. In metallurgical apparatus, a hearth comprising a trough for holding a smelting charge, a shovel comprising an arm and a blade disposed substantially perpendicular to said arm, means for operating said shovel to forma surface on said charge having a direction substantially the same as said arm.

29. In metallurgical apparatus, a hearth comprising a trough, a shovel comprising an arm and blade, said arm disposed generally horizontally and at substantially the same level as said trough and transverse to the length of said trough, means for imparting a motion to said shovel lengthwise of said arm to cause said blade 'to move back and forth across said trough, and means for imparting a second motion to said shovel transversely of said arm.

30. In metallurgical apparatus, a hearth comprising a trough, a shovel comprising an arm and blade, said arm being disposed generally horizontally and at substantially the same` level as said trough, means for imparting a motion to said shovel substantially lengthwise of said arm to cause said blade to move back and forth across said trough.

31. In combination with a hearth, mechanical 5 operating mechanism comprising a support, an impeller arm, a pivot connecting said arm to said support, means for imparting an oscillatory rotary motion about said pivot to said impeller arm, an operating arm having a shovel thereon, a 10 cam, means for rotating said cam, a cam follower,

a link, spaced pivots connecting said operating arm respectively with said impeller arm and link, and means connecting said follower and link to impart a reciprocating motion to said link. l5

32. In combination with a hearth having a longitudinally extending trough, mechanical shovel mechanism comprising a carriage adapted to movev along in front of said hearth, a shovel arm disposed generally horizontally and having a shovel blade at its back end, means for imparting a general reciprocating motion to said arm in the general direction of the length thereof to cause said blade to move back and forth across said trough, and elastic means for causing said blade to yield upon contact with an obstruction.

33. A smelting furnace comprising, a hearth adapted to receive molten metal upon which floats the material to be smelted, a carriage mounted for movement along said hearth, a backing de- 30 vice mounted on said carriage Iand adapted to push back the charge on said hearth, a crank, a lever connecting said crank with said device, a cam, and a link connected with said device and controlled by said cam.

34. A smelting furnace comprising, a hearth adapted to receive molten metal upon which floats the material to be smelted, afcarriage mounted for movement along said hearth, a backing device mounted on said carriage and adapted to push back the charge on said hearth, a crank, a lever operated by said crank and pivoted said device,

a link pivoted to said device, and a cam adapted to operate said link.

' 35. A smelting furnace comprising, a hearth 45 adapted to receive molten metal upon which floats the material to be smelted, a carriage mounted for movement along said hearth, a backing device mounted on said carriage and adapted to push back the charge on said hearth, a crank, a lever operated by said crank and pivoted to said device, a cam, a guide having a roll engaging said cam, and a link connecting said guide with said device.

36. In metallurgical apparatus, a Scotch hearth comprising a comparatively long and narrow trough for containing a smelting charge, a hood fitting closely thereover, a shovel comprising an arm and a blade disposed substantially transverse to the' arm, said arm being disposed generally 60 horizontally and at substantially the same level as said trough, and means for operating said shovel to form a surface on said charge having a direction substantially the same as said arm.

37. In metallurgical apparatus, a Scotch hearth 55 comprising a horizontally extending trough for containing a smelting charge, a shovel comprising an arm and a blade, said arm being disposed generally horizontally-and at substantially the same 38. In metallurgical apparatus, a Scotch hearth` comprising a horizontally extending trough for containing a smelting charge, a shovel comprising an arm and a blade, said arm being disposed generally horizontally and at substantially the same` level as said trough, a support in front of and above said'trough, an mpeller arm pivotally sus-- pended from said support, a link also pivotally suspended from said support, said shovel arm being pivoted to the lower ends of said impeller arm and of vsaid link, means for impressing a motion on said impeller arm generally transverse of its length, and means for impressing a motion on said link generally lengthwise thereof.

HUGH R. MACMICHAEL. 

